For convenience of the user, a gate lock is usually mounted outside the existing rolling shutter gate, and a steel column used as the lock bracket must be embedded in the ground outside the gate. If the steel column is embedded in the stoop or in the sill, there is not only an aesthetical impact on the stoop but also increases chances of being stumbled over it and causing bodily injury to the people passing by. If the steel column is embedded beyond the stoop, then it must be extended to reach the sill. In this case, the joint between the steel column and the stoop is exposed and such an extended steel column will render the joint to be easily broken open by a picklock. Therefore the rolling shutter gate is rather easy to break open and dismantle, thereby causing a potential safety issue thereof. Chinese Patent No. 01214242.5 disclosed a built-in theft-proof fitting for the rolling shutter gate. The technical scheme adopted in the patent is to place the gate lock inside the gate so as to minimize the risk of being pried and enhance the security thereof. However, the locking and unlocking operations thereof have to be inconveniently carried out by the user in a narrow space between the lower edge of the rolling shutter gate and the sill thereunder. It has thus been a technical problem, which puzzled designers for a long time, in making a rolling shutter gate having a locking means that is convenient to use, more hidden from view and difficult to break open.